package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //缓存穿透
        //Shop shop = queryWithPassThrough(id);
        //Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
        //Shop shop = queryWithLogicalExpire(id);
        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        if(shop == null){
            return Result.fail("店铺不存在!");
        }
        return Result.ok(shop);
    }


    //逻辑过期解决缓存击穿
    /*private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    public Shop queryWithLogicalExpire(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1、从redis查询点评缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2、判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //3、未命中,直接放回数据
            return null;
        }

        //4、命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5、判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.1 未过期，直接返回店铺信息
            return shop;
        }
        //5.2 已过期，需要缓存重建
        //6、缓存重建
        //6.1 获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //6.2 判断是否获取锁成功
        if (isLock){
            //6.3 成功，开启独立线程，实现缓存重现
            CACHE_REBUILD_EXECUTOR.submit(() ->{
                try {
                    //重建缓存
                    this.saveShop2Redis(id,20L);

                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }
        // 6.4 放回过期的店铺信息
        return shop;
    }*/


    //互斥锁解决缓存击穿
    /*public Shop queryWithMutex(Long id){
        //1、从redis查询点评缓存
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2、判断是否存在
        if (!StrUtil.isBlank(shopJson)) {
            //3、存在,直接放回数据
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if(shopJson != null){
            //命中的是穿透生成的空对象
            return null;
        }

        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            //4、实现缓存重建
            //4.1 获取互斥锁
            boolean isLock = tryLock(LOCK_SHOP_KEY);
            //4.2 判断是否获取成功
            if (!isLock){
                //4.3 失败，休眠并重试
                Thread.sleep(50);
                queryWithMutex(id);
            }
            //4.4 成功，根据id查询数据库
            shop = getById(id);
            //模拟重建延迟
            Thread.sleep(200);
            //5、不存在,返回错误
            if (shop == null){
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //6、存在，写入redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);

        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7、释放互斥锁
            unlock(lockKey);
        }
        //8、返回
        return shop;
    }*/

    //缓存穿透
    /*public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1、从redis查询点评缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2、判断是否存在
        if (!StrUtil.isBlank(shopJson)) {
            //3、存在,直接放回数据
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if(shopJson != null){
            return null;
        }
        //4、不存在，根据id查询数据库
        Shop shop = getById(id);
        //5、不存在,返回错误
        if (shop == null){
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);

            return null;
        }
        //6、存在，写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7、返回
        return shop;
    }

    //获取锁
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    //释放锁
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }
     */



    public void saveShop2Redis(Long id,Long expireSeconds){
        //1、查询店铺数据
        Shop shop = getById(id);
        //2、封装逻辑时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3、写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }

    /**
     * 更新商铺信息
     * @param shop 商铺数据
     * @return 无
     */
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id == null){
            return Result.fail("店铺id不能为空！");
        }
        //1、更新数据库
        update(shop);
        //2、删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }
}
